Bryan Colangelo hardly uttered a word when Chris Bosh left the Raptors for the Heat in the summer of 2010. The Toronto general manager did not follow the lead of Cavaliers owner Dan Gilbert, who lambasted LeBron James for his “Decision’’ to join Bosh and Dwyane Wade in Miami.

Colangelo instead has decided to rebuild, hopefully using the draw of Toronto as a premier international city and plenty of salary cap space to lure a major free agent to Canada. That’s the plan, and until it pans out, the Raptors will try to entertain their rather diverse and neophyte fan base with young talent and the promise of better days.

The Raptors looked green and lacked chemistry in their two preseason games against the Celtics, but they rallied to win the season opener against the Cavaliers, perhaps an indication that they won’t be the worst of the Eastern Conference’s lottery-bound teams.

The Raptors have drafted their share of talent in Damon Stoudamire, Marcus Camby, Vince Carter, Tracy McGrady, and Bosh, but they haven’t been able to keep any of them long-term. They are still searching for an identity, and Colangelo feels they are close, despite the constant rebuilding.

“Obviously when I first got to Toronto [in 2006], I felt like the roster needed to be overhauled and we did that,’’ said Colangelo, the son of former Phoenix executive Jerry Colangelo. “And having a centerpiece like Chris made it easy to kind of get competitive quickly and that’s what happened.

“We went from 27 wins to 47 wins and made it back to the playoffs for the first time in five years. The following years didn’t work out so well because although we tried to bridge the gap with additional pieces, it just didn’t seem to come together to the extent that we were competitive enough.’’

The Raptors’ win total decreased the next two seasons and Colangelo couldn’t surround Bosh with a supporting cast good enough to compete with elite teams in the Eastern Conference. Then they missed the playoffs in 2009-10 by one game after Bosh missed the final week with a facial fracture.

Bosh’s free agency was obviously overshadowed by that of James, but it became apparent near the end of the season that returning to Toronto was less likely. And he joined Wade in Miami a day before LeBron made his “Decision.’’

“The catalyst of the rebuild was obviously Chris making the decision to leave,’’ Colangelo said. “And it was a perfect reason or segue to start this process.’’

Colangelo showed no reluctance in giving Bosh the benefit of a sixth contract year in Miami and executing a sign-and-trade to help replenish the Raptors’ roster. They received two first-round picks and a trade exception from the Heat. Toronto used the first pick on Lithuanian standout center Jonas Valanciunas, who opted to spend another season overseas.

The Raptors are banking that former No. 1 pick Andrea Bargnani, along with athletic shooting guard DeMar DeRozan and forward Ed Davis will develop in new coach Dwane Casey’s defensive-minded system. The Raptors have had no trouble scoring points but haven’t stopped anyone for years, even with Bosh.

Colangelo fired the friendly but overwhelmed Jay Triano to take a chance on Casey, whose first head coaching stint ended rather unfairly five years ago in Minnesota.

Casey was the de facto defensive coordinator with the Mavericks, and his system contained James and Bosh in last year’s NBA Finals.

“You can see it, watching it every day, you can see that things are starting to change,’’ Colangelo said. “It feels different. There is a little bit of a bend toward defense, obviously. We’re working on laying the foundation for the ramp-up and the ramp-up probably begins in earnest next year.’’

That’s when Valanciunas will arrive in Canada along with another projected lottery pick, and Toronto will have an estimated $20 million to spend on free agents when Leandro Barbosa comes off the books in the summer. So Colangelo will try to sell a major free agent on Toronto, something that has yet to be accomplished in the franchise’s 16 years.

Waiting for all that, said Colangelo, “is really the only thing to do right now. It’s a deep draft and we’re going to get a quality player coming in. I really feel like we’re poised well for the future - just maybe a couple of bumps in the road here over the next four months.’’

Why Toronto has never attracted a major free agent is puzzling. The city is considered one of the best in the world for quality of life, it’s a short flight from the East Coast cities, and the Air Canada Centre is one of the league’s most sparkling arenas. But there remains a stigma to playing in Canada - that you’re playing in front of hockey-crazed crowds that view basketball as more of a novelty.

Bosh had never indicated earlier that he would leave Toronto.

“Chris left in what I would call a very unique set of circumstances,’’ Colangelo said. “It was a free agent frenzy. It was an unprecedented moment in this type of activity and he ended up going to be part of a rock-and-roll band in Miami. And it’s probably a decision nine out of 10 guys would make. And Chris again probably felt like that was the best thing for him.

“I’ll be honest with you, we were in a different set of circumstances not being able to do a whole lot for him because he never told us that he was going to be leaving or wanted out. He always made the impression very known and very public that he liked Toronto a lot and wanted to stay.’’

Colangelo did not hide his belief that Bosh is not an elite player or franchise cornerstone.

“Even if there was an open market similar to what’s gone on with [Carmelo Anthony] last year and Chris Paul this year and Dwight Howard, he’s not that caliber of player,’’ the general manager said. “It’s just that simple.

“I never had an opportunity to move him for the kind of haul that some of these other deals are producing. But for us to end up with a couple of first-round picks, it was a nice way to segue toward the future.

“As long as we weren’t strapped with a $126 million contract and the inability to really build around the player, we feel like this is probably the best thing that could have happened to us.’’

IN POST POSITION

Humbled Heat remake offense

The Heat, in a new humbled state since their disposal in the Finals at the hands of the Mavericks, prepared for this season as if the last one never happened. While they are the prohibitive favorites to win the Eastern Conference, there is a large sense of embarrassment still hovering around AmericanAirlines Arena after the Heat melted in the final three games against Dallas.

In the offseason, coach Erik Spoelstra changed the offense to emphasize LeBron James and Dwyane Wade in the post. While both are streaky 3-point shooters - James shot down the Celtics in Game 5 of the Eastern Conference semifinals - neither attempted a 3-pointer through the first three games.

James especially is flourishing in the offense, averaging 33.0 points and shooting nearly 60 percent from the field. Wade is shooting 47 percent and appears to be taking more time to get comfortable in the new role.

With James and Wade in the post, Chris Bosh may be pushed to the perimeter. He is playing more center down the stretch of games as Spoelstra uses Udonis Haslem at power forward and replaced Joel Anthony with Bosh.

Bosh has a polished perimeter game, but the Heat didn’t exactly sign him to launch long jumpers off the break.

“It’s a feeling-out process,’’ said Bosh. “With this offense I’m going to be trailing a lot. So it takes some getting used to. Sometimes it’s a race to the post and those guys [James and Wade] are fast, so nine times out of 10, I’m not going to beat them there.

“The way we’re structured, I have to kind of pick and choose my spots a little more. That’s kind of what we signed up for when we came here, is being more efficient.’’

Although they eliminated Boston in five games last season and the Celtics enter the season another year closer to a major roster adjustment, the Heat hold their rivals in high regard.

“Any time you play Boston, you know you’ve got to have mental and physical endurance throughout the whole game,’’ James said. “I think they always have to be talked about when you have three Hall of Famers and an All-Star point guard who can play at a high level and put up numbers any given night.

“You have to worry about them. We’re going in with the same mind-set as we did last year in the playoffs.

“You can take some of the things from last year’s series but not all of it. It’s a new season and you have to prepare differently.’’

The Celtics actually played better in that Eastern semifinal than the four-games-to-one result indicated. They were close to winning Games 4 and 5 before collapsing down the stretch. A Rajon Rondo missed layup in the final minutes of regulation of Game 4 could have sealed it.

“We had it going in the playoffs last year,’’ Wade said. “But especially Game 4 up in Boston was a very close game that they were winning. We happened to make the plays to come back and win it in overtime.

“But with a series like that, even the Chicago series, when you win, 4-1, it seems like a bigger margin than it really was. It takes a lot and those little things.

“[The Celtics] have a championship DNA. Rondo is really a problem for everyone around the league. He makes those guys’ jobs a little easier. A tough team.

“They’ll be a threat as long as they have those guys on the court together. I don’t know why the outside has been counting them out. They have been counting them out for about three years now. They are a very good team.

“When you have the history, when you have the confidence they have, when you have the championship DNA, and you have the coach that they have, you give yourself a chance every year.

“Sometimes you lose, it could be the difference of a rebound. It’s something that small.

“As long as Boston is together, whether it’s their last year together or whether they got three more, you never know with those guys. They are going to be someone you have to worry about.’’

ETC.

Sick and tired in first game

Former Boston College center Sean Williams has returned to the NBA, signing a contract with the Mavericks as a very-poor man’s replacement for Tyson Chandler. In his first appearance of the season - a blowout loss to the Nuggets - Williams literally lost it near the Dallas bench, vomiting after playing 11 minutes because he wasn’t in game shape. The incident caused laughter among the Mavericks but the matter may not be so funny for Williams, who has been banished from the league before for his flaky ways and now may be getting his final chance.

Starting over

Two former NBA players, including a former Celtic, are trying to revive their careers in the NBADL. Ricky Davis, who had all the talent and athleticism but not the desire, signed with the Maine Red Claws, the D-League affiliate of the Celtics. Davis scored 6 points in 25 minutes in his debut Thursday against Canton. Remember, Davis left Iowa after his freshman season. He is only 32 years old but has played 736 NBA games over 12 seasons. He spent two rather forgettable years with the Celtics before being traded to Minnesota, where he briefly played with Kevin Garnett. Also, former Jazz center Greg Ostertag joined the Texas Legends and scored 2 points with 11 rebounds in 17 minutes in his debut against Rio Grande Valley. Ostertag will be 39 in March, and it’s a testament to the lack of true big men in pro basketball that he’s even getting a look. The NBADL showcase is Jan. 9, and every NBA team will be represented. Davis and Ostertag will get long looks.

Layups

Gerald Green’s return to the NBA was short-lived. He was waived before the Lakers’ season opener and joined the NBADL’s Los Angeles D-Fenders. Green doesn’t turn 26 until next month but he may be running out of chances. The Celtics, Timberwolves, Rockets, Mavericks, and now Lakers have passed on his athleticism. As Mavericks owner Mark Cuban said, Green has all the physical skills but lacks the basketball IQ . . . Two former Celtics are available on the free agent market but neither is likely to return to Boston. Eddie House was released by the Heat, a byproduct of another pre-training camp surgery, this time on his left knee. House began last year with a shoulder injury that required surgery. With the emergence of Norris Cole, the Heat were full of guards, making House expendable. Also, Nate Robinson was bought out by the Thunder and is without a team. Robinson has often been criticized for his immaturity, especially with the Celtics, but he can be a productive player in the right system. With Keyon Dooling, E’Twaun Moore, and Avery Bradley, the Celtics are solid at backup point guard. Shaquille O’Neal’s book detailing some of the road stories about Robinson’s antics didn’t help his reputation, either. He will have to prove that he is able to handle the responsibility of playing in the NBA.

Gary Washburn can be reached at gwashburn@globe.com. Material from interviews, wire services, other beat writers, and league and team sources was used in this report.